Submission #395163

#	Time	Username	Problem	Language	Result	Execution time	Memory
395163		rqi	Parachute rings (IOI12_rings)	C++14	100 / 100	582 ms	49172 KiB

rings

#include <bits/stdc++.h>
using namespace std;

typedef pair<int, int> pi;
typedef vector<int> vi;
typedef vector<pi> vpi;

#define mp make_pair
#define f first
#define s second
#define pb push_back

#define sz(x) (int)(x).size()

int& ckmax(int& a, int b){
	a = max(a, b);
	return a;
}

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;

template<class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const int mx = 1000005;
int N;
vpi eds;
vi cands;
int max_deg;
int deg[mx];




pi beg_other_end[mx]; //other end, cycle size
int cyc_num = 0;
int cyc_size = 0;

void addToBegGraph(int A, int B){
	if(beg_other_end[A].f == B){
		assert(beg_other_end[B].f == A);
		cyc_num++;
		cyc_size = beg_other_end[A].s;
	}
	else{
		int tot_size = beg_other_end[A].s+beg_other_end[B].s;
		int a = beg_other_end[A].f;
		int b = beg_other_end[B].f;
		beg_other_end[a] = mp(b, tot_size);
		beg_other_end[b] = mp(a, tot_size);
	}
}

void Init(int _N) {
	N = _N;
	for(int i = 0; i < N; i++){
		beg_other_end[i] = mp(i, 1);
	}
}

bool cand_bad[4];
int cand_other_end[4][mx];

void addToCandGraph(int cand_num, int A, int B){ //update cand_bad
	if(cand_bad[cand_num]) return;
	if(cand_other_end[cand_num][A] == -1 || cand_other_end[cand_num][B] == -1){
		cand_bad[cand_num] = 1;
		return;
	}
	if(cand_other_end[cand_num][A] == B){
		assert(cand_other_end[cand_num][B] == A);
		cand_bad[cand_num] = 1;
		return;
	}
	int a = cand_other_end[cand_num][A];
	int b = cand_other_end[cand_num][B];
	cand_other_end[cand_num][A] = cand_other_end[cand_num][B] = -1;
	cand_other_end[cand_num][a] = b;
	cand_other_end[cand_num][b] = a;
}



void Link(int A, int B) {
	eds.pb(mp(A, B));

	if(max_deg >= 3){
		for(int i = 0; i < sz(cands); i++){
			if(A != cands[i] && B != cands[i]){
				addToCandGraph(i, A, B);
			}
		}
	}
	else{
		deg[A]++;
		deg[B]++;
		ckmax(max_deg, max(deg[A], deg[B]));
		if(deg[B] == 3){
			swap(A, B);
		}
		
		if(deg[A] == 3){
			//start phase 2
			cands.pb(A);
			for(auto u: eds){
				if(u.s == A) swap(u.f, u.s);
				if(u.f == A){
					cands.pb(u.s);
				}
			}
			assert(sz(cands) == 4);

			for(int i = 0; i < 4; i++){
				for(int j = 0; j < N; j++){
					cand_other_end[i][j] = j;
				}
				for(auto u: eds){
					if(u.f != cands[i] && u.s != cands[i]){
						addToCandGraph(i, u.f, u.s);
					}
				}
			}
		}
		else{
			//continue phase 1
			addToBegGraph(A, B);
		}
	}

	
}

int CountCritical() {
	if(max_deg >= 3){ //phase 2
		int ans = 0;
		for(int i = 0; i < 4; i++){
			if(!cand_bad[i]){
				ans++;
			}
		}
		return ans;
	}
	
	//phase 1
	if(cyc_num == 0){
		return N;
	}
	if(cyc_num == 1){
		return cyc_size;
	}
	return 0;
}

• Subtask 1: 20 / 20
• Subtask 2: 17 / 17
• Subtask 3: 18 / 18
• Subtask 4: 14 / 14
• Subtask 5: 31 / 31